Control of detergent properties in a spray dryer process

EngDThis research details the building, implementation and validation of models designed for the control of specific powder detergent properties in a spray dryer process. Findings are reported in two sections; the control of moisture content, particle size distribution (PSD) and bulk density properties; the development of a process model for the online estimation and simulation of the process. The project was completed at Procter & Gamble’s Newcastle Innovation Centre, using a mixed flow spray dryer for the case study. Moisture content can be controlled using a soft sensor to enable estimation of this parameter at a higher sampling frequency than manual measurements of the powder. The proposed empirical model proved to be the most successful approach compared to heat and mass balances. Each model required adjustment of a parameter following the first manual measurement of moisture in a batch run. Control of PSD can be achieved through analysis of droplet size distribution. The dominant influence on the final PSD is the atomization of the slurry, which can be manipulated through changes to the ratio of air and slurry flow to the nozzle. However, numerous sources of variability necessitate continuous amendments to the atomizing air flow rate to maintain the PSD at the required target value. The use of an automatic cascade loop control strategy facilitated manipulation of the air flow to the nozzle, improving control of PSD considerably, halving the response time and reducing variability of mean particle size. Control of bulk density is dependent on an understanding of the key factors that determine the final density of the powder. The density model proposed incorporates statistics for the impact of packing, air entrapment and drying. The model details the limits of the rate of air injection into the slurry, its influence on density control and provides explanations for density changes during the process. viii Separate studies demonstrate the influence of each property on process conditions in each compartment of the mixed flow spray dryer. A model linking these properties to the process conditions has been formulated to provide optimal control strategies for the process. The spray drier involves 3 compartments; a spray chamber, an inner fluid bed and an outer fluid bed. Computational fluid dynamics are used to estimate flow properties and residence times of the chamber and a CSTR model is used to model the fluid beds. The constant drying rate curve (CDRC) and reactor engineering approach (REA) drying models have been implemented and fitted using historical data. A sigmoidal model approach to the CDRC has been included to enable a smoother transition between the constant and falling rate periods. Simulation of the process and online estimations of the powder’s properties were assessed. In each batch, the CDRC model provided the most accurate representation of the process. The CDRC model is recommended for control of the spray drying process and in simulation studies

Study of tablet coating using high-speed air fluidization technique

Ph.DDOCTOR OF PHILOSOPH

Freezing and Optical Properties of Model Atmospheric Aerosols

The freezing of model atmospheric aerosols – specifically, model cirrus cloud particles – was investigated through laboratory studies of supercooled water aerosols. Water droplets with radii of 1 – 2.7 µm were exposed to well-defined temperature profiles ranging from 240 – 230 K in a cryogenic flow tube apparatus, and observed using infrared extinction spectroscopy. A computational characterization procedure, based on theories of light scattering, was used to determine the size and phase composition of aerosols from extinction spectra. The procedure showed large ice fractions at uncharacteristically warm temperatures, which was attributed to the formation of ordered, “ice-like” clusters of molecules in supercooled water. Temperature-dependent complex indices of refraction were determined from the supercooled water extinction spectra, and showed changes reflecting this ordered formation. Taking the “ice-like” character of clusters into account, the homogeneous nucleation point for micrometre-sized water aerosols was determined to be 236.2 K. A microphysical model was developed to determine temperature-dependent, volume- and surface-based homogeneous nucleation rates from experimental freezing data. The model results indicated that surface nucleation was the dominant process for our range of experimental conditions. This was supported by separate studies of smaller, 0.63 and 0.75 µm radius aerosols, with larger surface-to-volume ratios. An optical microscopy apparatus was placed in the cryogenic flow tube to allow real-time imaging of particles in freezing experiments. The imaging studies demonstrated the utility of the microscopy apparatus for the observation and classification of ice crystal habits. Ray tracing and image processing algorithms were used to analyze particle geometry and size. The latter was used to validate the size retrievals from the aerosol characterization procedure. Additional studies probed the changes in the optical properties of crystalline ammonium sulfate, (NH₄)₂SO₄, due to the paraelectric-to-ferroelectric transition at 223 K. Temperature- dependent refractive indices were determined from crystalline (NH₄)₂SO₄ extinction spectra. Only small changes in these values were observed down to 223 K, below which significant changes were observed, due to the changes in lattice structure accompanying the ferroelectric transition

“In situ monitoring of pharmaceutical operations”

The subject of the thesis is the examination of the phenomena behind the formulation and spatio-temporal evolution of anisotropic particle assemblies during drying processes. Two different drying processes have been investigated in this study, namely spray drying and contact drying. Following a literature review of the relevant processes – namely spray drying but also particle agglomeration and break-up, literature on the packing of non-spherical particles is reviewed. An investigation into the effect of particle shape, solubility, initial concentration and state (solution vs. slurry), and drying rate on the microstructure of particle assemblies within an evaporating droplet has been carried out. The materials used in the study were chosen so as to cover a range of solubility and crystal shape, and include: benzoic acid (needle shaped) and glass beads (spherical shape), monosodium glutamate (MSG), lactose, hydroxypropylmethylcellulose (HPMC), aspirin, sodium carbonate and water. The study of single droplet drying aims to provide a quantitative and qualitative view on the microstructure formation during drying. A new single droplet drying technique has been developed to allow for real-time observation of the microstructure and morphology evolution, and subsequently to determine whether the particle morphologies produced in single droplet drying are analogous to those produced by a spray dryer. The results produced in this study indicate that for the materials investigated, the end microstructural arrangement obtained by the single droplet technique will be essentially the same as that obtained in a spray dryer, and the single droplet method can therefore be used as an early indication of the most likely particle morphology. This has significance during process scale-up in the pharmaceutical industry and in other situations when only small quantities of a newly developed chemical entity are available but a decision about the process route has to be made at an early stage. The single droplet results have also allowed for the understanding of some drying mechanism behind the morphologies commonly produced in spray drying

Fingerprinting of Materials: Technical Supplement

This supplement to the Guidelines for Maintaining a Chemical Fingerprinting Program has been developed to assist NASA personnel, contractors, and sub-contractors in defining the technical aspects and basic concepts which can be used in chemical fingerprinting programs. This material is not meant to be totally inclusive to all chemical fingerprinting programs, but merely to present current concepts. Each program will be tailored to meet the needs of the individual organizations using chemical fingerprinting to improve their quality and reliability in the production of aerospace systems

Plasma Spectroscopic Techniques Applied to Biological and Environmental Matrices

The purpose of this research was to apply the use of direct ablation plasma spectroscopic techniques, including spark-induced breakdown spectroscopy (SIBS) and laser-induced breakdown spectroscopy (LIBS), to a variety of environmental matrices. These were applied to two different analytical problems. SIBS instrumentation was adapted in order to develop a fieldable monitor for the measurement of carbon in soil. SIBS spectra in the 200 nm to 400 nm region of several soils were collected, and the neutral carbon line (247.85 nm) was compared to total carbon concentration determined by standard dry combustion analysis. Additionally, Fe and Si were evaluated in a multivariate model in order to determine their impacts on the model\u27s predictive power for total carbon concentrations. The results indicate that SIBS is a viable method to quantify total carbon levels in soils; obtaining a good correlation between measured and predicated carbon in soils. These results indicate that multivariate analysis can be used to construct a calibration model for SIBS soil spectra, and SIBS is a promising method for the determination of total soil carbon. SIBS was also applied to the study of biological warfare agent simulants. Elemental compositions (determined independently) of bioaerosol samples were compared to the SIBS atomic (Ca, Al, Fe and Si) and molecular (CN, N2 and OH) emission signals. Results indicate a linear relationship between the temporally integrated emission strength and the concentration of the associated element. Finally, LIBS signals of hematite were analyzed under low pressures of pure CO2 and compared with signals acquired with a mixture of CO2, N2 and Ar, which is representative of the Martian atmosphere. This research was in response to the potential use of LIBS instrumentation on the Martian surface and to the challenges associated with these measurements. Changes in Ca, Fe and Al lineshapes observed in the LIBS spectra at different gas compositions and pressures were studied. It was observed that the size of the plasma formed on the hematite changed in a non-linear way as a function of decreasing pressure in a CO2 atmosphere and a simulated Martian atmosphere

Bibliography of Lewis Research Center technical publications announced in 1980

This compilation of abstracts describes and indexes over 780 research reports, journal articles, conference presentations, patents and patent applications, and theses resulting from the scientific and engineering work performed and managed by the Lewis Research Center in 1980. All the publications were announced in Scientific and Technical Aerospace Reports and/or International Aerospace Abstracts

Video Games for Earthly Survival: Gaming in the Post-Anthropocene

In this paper I evaluate the sixth mass extinction on planet Earth, and its implications for the medium of the video game. The Anthropocene, a term popularized by the end of the 20th century to refer to the geological impact of human beings on planet Earth, assumes temporal development, a ‘before’ and ‘after’ the appearance of humankind. The ‘after’ period, the Post-Anthropocene, is repeatedly claimed by scientists to be approaching within the next few decades, as over-consumption is destroying vital resources of the planet. Allegedly, the sixth mass extinction in the history of our planet is already unfolding, and might determine the disappearance of life from Earth and, as far as we know, from the Universe and beyond. Video games responding to the arrival of the future is not just imagined in fictional settings (e.g. The Legenda of Zelda: Majora’s Mask, Nintendo, 2000; Horizon: Zero Dawn, Guerrilla Games, 2017), but within game design. In the last decade an increasing number of video games requiring limited human intervention has been released. Incremental/ idle games such as Cookie Clicker (Julien Thiennot, 2013) and AdVenture Capitalist (Hyper Hippo Productions, 2014) require an initial input from the player to start, and then keep playing themselves in the background operations of a laptop or smartphone. Virtual environments can be entirely designed by algorithms, as experimented by Hello Games for No Man’s Sky (2016). Artificial Intelligence is also used to play games. Screeps, a massive-multiplayer online game, requires players to program an AI that will play the game in their place, and which will “live within the game even while you are offline” (Screeps Team, 2014). Ghost cars in racing games replace the human actor with a representation of their performance. The same concept is further explored by the Drivatar of the Forza Motorsport series (Microsoft Studios, 2005-2017), which simulates the driving style of the player and competes online against other AI-controlled cars. These are only some of the examples that suggest that human beings are becoming peripheral in the act of playing games. In short, it is probably becoming ‘easier to imagine the end of the world than the end of gaming’. While studies on games with no players, and on the non-human side of gaming, have been proposed in the past, my presentation takes a non-normative and non-systemic approach to the study of games for the Post-Anthropocene. I am concerned with the creative potential of the paradoxes, spoofs, and contradictions opened by games that take Man/Anthropos as being no longer at the centre of ‘interaction’, ‘fun’, and many other mythological aspects of digital gaming. Nonhuman gaming questions the historical, political, ecological and even geological situatedness of our knowledge on games and gamers, interaction and passivity, life and death

The Paranoiac-Critical Method of Reflectance Transformation Imaging

A performative talk examining Reflectance Transformation Imaging (RTI), an open source computational photographic process that is transforming methodologies in archaeology and heritage conservation for its ability to interactively re-light artefacts within a virtual hemisphere of illumination and extrude a digital topography that is hyper-legible in space-time, from its contemporary application in facial recognition via Bertrand Tavernier's 1980 science fiction film La Mort en Direct and a return of the death mask through digital extrusion, ultimately locating a progenitor of the heightened objectivity promised by RTI paradoxically in Surrealist photography and the fugitive facialities of Salvador Dali's Paranoiac-Critical Method. As emerging imaging technologies such as RTI are seen to open novel ways of extracting latent data from historical artefacts, reassembling objects of study in a new (virtual) light, collateral opportunities provided by these technologies to re-enter archival still and moving image recordings inadvertently recalibrate their spatio-temporal ground and destabilise their indexical reading through an excessive production of new traces and signs. If methodologies can be seen to play a significant role in constructing their objects of study, then emerging computational imaging operations such as RTI have their own subjectivities to disclose: In performing a media archaeology of this digital process, the talk proposes that we not only narrate the subjects of our study but the very tools of investigation themselves